Influence of unbalanced operation time means and uneven buffer allocation on unreliable merging assembly line efficiency

Abstract

Unbalanced, unreliable (UR), unpaced, merging assembly lines are simulated in this study with varying line lengths, buffer storage capacities, imbalance degrees and unequal mean operation time configurations and uneven buffer capacity (BC) allocation. This paper contributes to the literature by suggesting that, in many cases, imbalance can improve merging lines' performance, as compared to a corresponding balanced merging line. It was found that an inverted bowl or descending patterns for mean operation times (MTs), and an inverted bowl (concentrating BC towards the centre of the line) or an ascending pattern for buffer allocation, result in higher throughput (TR). In terms of average buffer level (ABL), the best pattern is a monotone decreasing order regarding MTs and a monotone increasing order with respect to BC allocation. Additionally, it was found that when considering a profit function, the best performing patterns for UR lines tend to be the patterns that reduce ABL, even when considering very low inventory holding costs; contrary to the behaviour of the profit function in reliable lines, which suggests that either patterns that increase TR or reduce ABL can lead to a good performance, depending on the values of the unitary inventory holding costs.

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Implementation of Lean Methodology on the Main Assembly Line of an Automotive Plant to Enhance Productivity

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“…This behaviour can lead managers to find trade-offs between opposing performance effects or to find the best solution regarding an all-encompassing measure of system performance, e.g. the trade-off in terms of profit between the investment and inventory-holding costs of higher buffer capacity and the added revenue resulting from higher throughput created by the extra buffer capacity (see, e.g., [75,112,113]).…”

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